Molybdenum is frequently copresent with uranium in uranium ores and is partially coextracted in the uranium leach liquors. In order to provide a commercially acceptable uranium product, the molybdenum content in the leach liquor is controlled to low levels, e.g., 20 parts per million (ppm). The molybdenum content in the leach liquor is maintained at such low levels by passing the leach liquor through an ion exchange resin or through a char column. When the ion exchange resin or the char become loaded, the resin or char is stripped to provide an aqueous molybdenum containing solution. Stripping is frequently conducted in such a fashion that the strip solution contains only small amounts of uranium and molybdenum and is disposed of in deep wells.
It has recently been discovered that by employing a two-stage strip--the first on the acid side and the second on the basic side using ammonium hydroxide--uranium and molybdenum can be selectively stripped to provide strip solutions having useful concentrations of these metals. Selective stripping is more fully described in U.S. Patent Application, Ser. No. 869,338, filed Jan. 13, 1978, which is incorporated herein by reference.
Although selective stripping as described in the aforementioned patent application provides ammonium molybdate solutions that can be readily treated for molybdenum recovery, the amount of molybdenum co-produced with uranium is comparatively small and any process for recovering and refining such small amounts of molybdenum must be simple with small capital requirements to be economically viable. Not only must the process be simple but it must also be effective in producing a molybdenum product having exceptionally low levels of phosphorus, sulfur, lithium, sodium, potassium, and uranium.